The most appropriate key risk indicator (KRI) for backup media that is recycled monthly is the percentage of failed restore tests. A KRI is a metric that measures the likelihood or impact of a risk, and provides an early warning signal of a potential risk event. The percentage of failed restore tests is a KRI that reflects the quality and reliability of the backup media, and indicates the possibility of data loss or corruption. A high percentage of failed restore tests would suggest that the backup media is not functioning properly, and that the risk of data unavailability is increasing. Therefore, this KRI would help the risk practitioner to monitor the risk and take corrective actions as needed. References = Risk and Information Systems Control Study Manual, 7th Edition, Chapter 5, Section 5.2.2, page 235.